Material for intiating a welding arc



Patented Nov. 29, 1938 MAT John D. Crecca and Samuel S. Scott, St.Albans,

No Drawing. Original application January 13,

1934, Serial No. 706,510.

Divided and this application June 19, 1936, Serial No. 86,152

3 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757) This invention relates to material for initiating the arebetween two bodies that are to be electrically welded together,particularly when one of those bodies is of relatively small crosssectional r area. on the surface thereof to be joined to the other body,such as a stud, while maintaining the two bodies spaced apart a distanceequal to the proper length of the welding arc and without establishing asolid conductivev connection between the two bodies.

It is the object of this invention to provide a material of the kind andfor the purpose specified to facilitate those welding operations towhich it is adapted and to secure a greater percentage of sound, strongwelds by making it possible to space accurately the. bodies to be weldedbefore the welding current is turned on.

This is a division of our copending application, Serial No..706,510,filed January 13, 1934, since matured into Patent No. 2,057,670, datedOct.

While the present invention is particularly adapted for use with weldingapparatus of the type disclosed in our said copending application, itsusefulness is not limited thereto, but it may be applied in many waysthat will suggest themselves to those skilled in this art. For purposeof illustration only, and not byway of 1imi-. tation, the invention willbe described in connection with the welding of a stud or the like to aplate. In such cases it is the usual practice to use the stud to bewelded as an electrode, and it will hereinafter be so designated.

A material that we have found to be very satisfactory for this purposeis .two parts of steel chippings and one part of aluminum filings;

however, these terms are not to be taken as re-- strictive of the formof themetal particles since these particles may be granular,filamentary, or

laminar; and should be of a size larger than will pass through a number8 mesh screen. The aluminum serves as a scavenger of oxygen and toprevent porosity of the weld, while the iron supplies additional bondingmaterial. A small quantity of the material is placed upon the plate atthe situs of the weld and the electrode is then properly positioned withrespect to the plate with the end of the electrode spaced from the platea distance equal to the proper arc length. The

arc-initiating material acts to cause the arc to be struck as soon asthe welding circuit is closed without the necessity of moving theelectrode into contact with the plate and withdrawingw it to the arcdistance after the current has begun to flow. This is due to the factthat the potential across the arc space sets up a flux that moves theparticles of the-material to short circuit the gap. For welding ahalf-inch stud, about 150 milligrams of the arc-initiating material issuflicient;

if too great a quantity be used, the molten metal will splash and mayfreeze on the threads of the stud. The aluminum acts as a scavenger'ofoxygen and so assists in forming strong, non-porous welds. The ferrousmetal used should be free of oxide. Instead of making a heap of the arcinitiating material upon the surface of the plate, the material may becaused to adhere to the end of the electrode by means of glue,glycerine, or other adhesiye.

This invention may be manufactured or used by or for the Government ofthe United States of America for governmental purposes without thepayment of any royalties thereon or therefor.

We claimz 1. A material for initiating an electric arc while maintainingthe electrodes spaced apart, comprising a loose intermixture of steelchippings and aluminum filings substantially in the proportion of twoparts of. the former to one of the latter.

2. A material for initiating an electric arc while maintaining theelectrodes spaced apart, comprising a loose intermixture of ferrousmetal and an oxygen-scavenging metal, both in the form of filamentary,granular, or laminar particles, substantially in the proportion of twoparts of the former to one of the latter.

3. A material for initiating an electric arc between electrodesmaintained in spaced apart relation, comprising unconfined metallicparticles 40 which, when disposed between said electrodes in contactwith one therecfand "subjected to the flux due to a potential appliedacross the gap between said electrodes,-'-are movable by said flux toshort circuit the said gap and establish an arc.

JOHN D. CRECCA. SAMUEL S. SCOTT.

